Effects Resin Helps Spice Up Appearance Of Massage Product

When Wellness Innovations, a manufacturer of heavy-duty massagers for chiropractors, physical therapists, sports trainers, and professional athletes, went to update its flagship product, the Thumper Professional Massager, it wanted to visually convey the improvements. The use of a splashy special-effects resin helped to reinforce the new features of the updated model in customers’ minds, despite some tricky processing requirements.

The new model features a variable-speed control and is powered by a high-torque, permanent-magnet dc motor, says Edmond Lau, production manager for the company, which has a manufacturing facility in Markham, on, Canada, and a sales and service center in California. “The older model is a bone-white color, and [company founder Dr. Edward] Noble wanted something new for this product that would impress our customers,” says Lau. “In choosing the color, we looked at several selections, including a blue and black with a silver metal-flaked effect. They all looked great, but, in fact, a graphite color with silver sparkles was the best for the new unit.”

The company turned to Toledo, on-based custom injection molder Performance Plastics, and Clariant Masterbatches, Muttenz, Switzerland, to develop a special-effects color to bring some pizazz to the unit’s polycarbonate housing. Performance Plastics produces 100 different products with injection machines from 80 to 320 tons at its 19,000-ft2 facility. The 25-employee company also provides additional services such as hot-stamping, sonic-welding, screen-printing, and assembly.

“Our strategy is to be a partner with our customer, to provide as much of a turnkey operation as we can,” says Performance Plastics president Lou Coppa. “Where it’s justified, we’ll even set up a separate [production] line, and we can ship right to the distributor or outlet.”

For the massager, Clariant sales representative Gary Mercer says it developed a masterbatch with a silver-coated fiber to produce the metal-flake effect. “Processing the fiber into the polycarbonate is tricky,” he says. “One of the challenges is to maintain particle size because polycarbonate is such a stiff resin.” Due to the metal-coated fiber, the material had to pass UL tests for spark and discharge, which Clariant secured, Coppa says.

The housing components are made on a 320-ton Mitsubishi press with a masterbatch let-down ratio of 4%. “We had to make some changes in how we ran the parts,” Coppa notes. He explains that screw design was particularly important when working with the special-effect resin. “A low-compression screw should be used with polycarbonate, in general, but even more so with the metal fleck, because it tends to plasticize more evenly,” he explains. “You have less shear and more even distribution of particles. By nature, the particle distribution is random, but with the proper process they are spread evenly.”

Maintaining the proper heat is important to prevent the particles from accumulating in the weld lines. “One of the drawbacks to working with this type of special effect is that you get buildup,” Coppa says, “but that was easily handled by lowering the screw speed and the injection rate because of the way these molds are gated.” Each part has two 0.06- by 0.06-in gates, which he says are quite small for polycarbonate. The total weight of both parts is 672 g.

“Even though we want a degree of uniformity, one of the beauties of working with this kind of special effect is that each unit is unique, almost personalized,” says Coppa. “When you get the right combination of colors and effects, it makes a difference like day and night.”